Route reliability record

DTW→DEN

Detroit to Denver

Flights: 3,089
Period: July 2025 to June 2026
Distance: 1,123 mi
Carriers: 5

This route lands a B+, 2 points better than the national rate of 77.6%. About one flight in five arrive 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 3,089 flights, of which United Airlines flew 727 at 83.7% on time.

United Airlines is the most reliable of the four carriers covered here at 83.7% on time across 727 flights.

On time

79.7%

Arrivals under 15 minutes late, of 3,058 completed flights

Avg delay

61 min

Across delayed arrivals only, not all flights

Cancelled

0.49%

National rate is 1.81%

Best carrier

United

83.7% on time across 727 flights

These figures cover 3,089 flights between July 2025 and June 2026. The median arrival is 5 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

Carrier by carrier

Which airline is most reliable on DTW to DEN

The choice of carrier is not cosmetic here. United Airlines arrives on time 83.7% of the time; Southwest Airlines manages 74.7%. Sample sizes sit next to every figure, because a two-point gap across 649 flights means less than a ten-point one.

On-time performance by carrier on DTW to DEN
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlinesthin sample	1	100.0%	—	0.00%	A+
United Airlines	727	83.7%	72 min	0.69%	B+
Frontier Airlines	459	83.2%	73 min	0.44%	B+
Delta Air Lines	1,253	78.6%	58 min	0.32%	B+
Southwest Airlines	649	74.7%	51 min	0.62%	C+

United leads Southwest by 9 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Departure window

The best time of day to leave

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 32 points, against 9 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am382 flights88.7%
8am–11am877 flights86.4%
11am–2pm603 flights85.5%
2pm–5pm779 flights74.2%
5pm–8pm242 flights56.7%
8pm–5am206 flights64.2%

Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 56.7% on time, against 88.7% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 8am–11am window is the busiest, with 877 flights scheduled in it.

Across the year

When delays peak on this route

This route's year swings by 27 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.

Darker means more delays. Figures are on-time percentages.September best, December worst

December is the weak month at 62.9% on time, against 89.5% in September. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. July was the busiest month here, with 288 flights.

Across the week, Wednesday is the strongest day at 82.1% on time and Sunday the weakest at 78.1%. 4 points is a smaller lever than departure hour, but it is free.

Delay causes

Why this route gets delayed

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 38,000 reported delay minutes.

Carrier
38%
National Airspace System
32%
Late-arriving aircraft
27%
Extreme weather
4%

32% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 12,000 minutes out of 38,000, against a national NAS share of 21%. The split is drawn from 37,644 reported delay minutes.

The largest share of delay minutes, 38%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 14,000 of the 38,000 delay minutes reported here.

Cancellations are rare at 0.49%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

Connections and stage length

What a delay here actually costs

6.0% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route are the about an hour kind, which a normal layover absorbs.

The 1,123 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The return leg runs 77.6% on time across 3,088 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

The sample behind these figures is 3,089 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.

What to do with this

Booking this route

Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 89.5% on time and December 62.9%, a swing of 27 points. If the dates move at all, move them out of December before you think about anything else. 3,058 completed flights over 12 months sit behind that.

Common questions

DTW to DEN questions

How often is DTW to DEN delayed?

About one flight in five arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 20.3% of the 3,089 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.

Which airline is most reliable on DTW to DEN?

United Airlines leads at 83.7% on time across 727 flights. Southwest Airlines is at the other end on 74.7%, a gap of 9 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.

What time of day has the fewest delays on DTW to DEN?

The 5am–8am departure window is the strongest at 88.7% on time. The 5pm–8pm window is the weakest at 56.7%, 32 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.

How bad are December delays on DTW to DEN?

December is the weakest month at 62.9% on time, compared with 89.5% in September. Across the year that is 27 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.

Where to go next

Direction matters. DTW to DEN and DEN to DTW are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.

Key figures